Ball joint coupling for trailers of motor vehicles



F. KNCBEL, JR

Jan. 10, 1939.

BALL JO INT COUPLING FOR TRAILERS OF MOTOR VEHICLES Filed Sept 4, 1956 BALI) Jonv'r COUPLING Foe. TRAILERS or MOTOR vculcms Franz K ni ibel, In, Wiedenbruck, Germany f; Application September 4. 1936, Serial No. 99.423 i .In Germanyflctober 29, 1934.

" 1 7 iclaim. (c1. 28 533.15)

The known ball joint couplings ,for trailers of motor vehiclesin which the ball member is'held in the ball cup member by means of a locking element, are, open to the objection that is is often forgotten'to operatethelocking lever with the result that the trailcr'can easily'beconie d ee tachcd and cause damage.

This objection is overcome by. the. invention,

fundamental idea. of. which 'is toallow a M) spring to act on the locking element which. is bloin a guide preferably at an angle to the 'tion of pull. this spring, which is also acodatcc i th casing of the locking isioncd during the opening of fit for the purpose of intro- "bcr of the tractor into the loans of a hand lever mounted casing and engaging by means 1113- in the locking element, and n the handle released, this rally brings the locking element 1g position and blocks the ball The is according to the in- .tion also constructed in such a manner that it bears against the ball member at two points distributed relatively to the locking element so as to avoid the rattling noises which were always present in the knovm ball joint couplings. According to another feature of the invention insulated contacts, electrically connected with he source of current of the vehiole, are provided at two opposite sides of the ball member and contact pins insulated and resiliently mounted in the cup member and conected with the stop and tail lights of the trailer, slide over these contacts, so that, when the trailer is being automatically coupled with the motor vehicle, the electric connection between. the trailer and the motor vehicle is established at the same time.

An embodiment of the invention is illustrated way of example in the acompanying drawing, in which-- Fig. 1 shows the coupling in side elevation.

2 is a top plan View of Fig. l. 3 is a front end. view of Fig. 1.

i shows the coupling in longitudinal section closed condition.

Fig. 5 is a similar view to Fig. 4, coupling in open condition. 7

Fig. 6 is a vertical section through the ball coupling taken transversely to the direction of duciog t cun ill on tho of an showing the pin 5 mounted on the draft rod t of the motor vehicle. According to the invention this ball joint coupling is automatically locked. For this purpose the wedge 6 constructed as looking mem be r is mounted in the housing 7 serving. as guide slidable against the action of a spring 8, and it can be brought into its open position (Fig. 5) by a hand lever 9, thereby tensioning the spring 8, whereas, when the handle 9 is released, the spring 8 presses the locking member 5 into its locking position (Fig.4) and holds it in this position. The loclring wedge. 6 is oscillatably mounted in holes in the hand lever B by means of pins ii engaging in guides ll] (Fig. 1) in the housing 2, the lever itself being rotatable about pins 32 mounted on the housing 2.

The ball cup 3 embracing the ball pin 5 is constructed in such a manner that it bears against the ball only at two points l3 and M which are spaced relatively to the spring loaded locking wedge 6 in such a manner that the three supporting points of the ball pin are uniformly distributed on the periphery of the embraced ball (see Fig. 4). By these three supporting points the ball pin is absolutely reliably guided and is free from rattling even when the points in question have worn in the course of time, as the strong spring 8 re-adiusts the locking wedge 6 corresponding to the wear. The hollow spaces formed by this construction of the ball cup can be filled with felt or the like saturated with oil.

The ball 5 has a horizontal bore 55 (Fig. 5) extending transversely to direction of pull and terminates in two diametrically opposite recesses in the ball surface, which recesses are each filled with an insulating piece iii preferably made of Bakelite. The insulating pieces [6 can easily be fitted and are held in position by means of a spiral spring 18 extending through the bore [5 and hooked into eyes I! one on the side of each insulating piece, whereas fiat or curved contact discs I9 are fixed. one on the outer side of each insulating piece. Electric leads 20 extending through a. bore 2! in the ball 5 and in the rod 4 are connected to these contact discs ii and to their terminals in the motor vehicle.

Contact pins 23 supported by springs 24 are mounted in holders 22 of insulating material anranged opposite the contact discs in the hemispherical cup 3 embracing the ball 5, so that these pins s ide on the contact discs H3. The two contact pins 23 are electrically connected with the "stop" and tail lights of the trailer by means of leads laid in grooves 25 in the housing 2, so

that, when the contact pins 23 bear against the contact discs 19, the circuit is closed.

The trailer coupling and the electric connections with the motor vehicle are manipulated and operate in the following manner.

For coupling the trailer with the motor vehicle, the hand lever B is raised and the locking wedge 5 is thereby pressed into the housing 1 until the ball pin 5 of the motor vehicle can be introduced into the hemispherical cup 3, the springs being at the same time compressed. The hand lever 9 is then released, whereupon the spring 8 automatically presses the locking wedge 6 into the locking position (Fig. 4) and establishes an absolutely reliable connection between the motor vehicle and the trailer. The trailer cannot possibly become uncoupled by vibrations during the travel as the ball 5 cannot shift the locking member 6.

The guiding surface for the locking member 6 may be constructed and arranged in any suitable manner, but its arrangement at an angle to the direction of pull presents the advantage that, although no locking pawls or the like are provided, the ball 5 cannot shift the locking member in any of the thrust directions coming into question.

During the introduction of the ball 5 into the ball cup, the resilient contact pins 23 automatically come into contact with the contact discs l9 and thus establish the connection between the tail light and stop light on the trailer and the source of current in the motor vehicle, so that the circuit is automatically closed by the hitching up of the trailer.

The arrangement of the contact discs I9 on the extremities of the horizontal diameter of the ball 5 extending transversely to the direction of pull presents the advantage that these points of the periphery of the ball are least stressed during travel. The contact discs l9 are preferably made so large that they remain in contact with the contact pins 23 during veering movements such as normally occur, and only move out of contact with the pins in very sharp curves and veering movements. It is evident that a sufficiently large insulated space must be provided between the ball surface and the contact discs to avoid shortcircuiting.

In a ball joint coupling for tractors of motor vehicles, comprising in combination a ball pin on one vehicle, a ball cup on the other vehicle adapted to receive said ball pin, a housing formed on said ball cup at an acute angle to the direction of pull, a bracket carried by the housing, a shaft to which the bracket is attached, a locking wedge slidable in said housing, a spring in said housing adapted to press said wedge outwards to lock said ball pin, a hand lever articulated to said housing, said housing having a slot therein extending lengthwise thereof, a pin extending through said slot for connecting the hand lever to the sliding wedge and said lever being engaged to said shaft when the sliding wedge is in looking position,engaged with the ball pin.

FRANZ KNOBEL, JUNIOR. 

